Such a tool holder serves in particular for receiving a comparatively small cutting insert with which grooves or plunge cuts may be created on a tool, in particular upon turning. To this end, the counter bearing segment and the clamping finger are designed to be very narrow, in particular much narrower than the shank with which the tool holder may be clamped to a machine tool, for example a lathe.
The coolant supply passage enables a coolant flow to be delivered to where the workpiece is being machined by the cutting insert. The clamping finger passage typically opens slightly above the cutting insert so the coolant flow is incident on the cutting face in the region of the cutting edge of the cutting insert. Embodiments are also known in which the clamping finger passage is formed partly between the clamping finger and a top side of the cutting insert.
Given tool holders of the type mentioned above, the problem arises that the coolant supply passage must extend from the shank as far as the clamping finger, and therefore through the bending segment. The bending segment should have a comparatively small material cross section, such that the forces provided by the clamping element (typically a clamping screw) may be translated mostly into a clamping force for the cutting insert and are not needed to overcome the resisting force of the bending segment. However, the connecting passage that extends through the bending segment places certain lower limits on the minimum cross section of the bending segment.
From WO 2012/171976, a tool holder of the type mentioned above is known in which the clamping segment is designed to be asymmetrical, namely having a web or projection on one side. The connecting passage is disposed within this region, such that there is still sufficient material on both sides of the connecting passage in the bending segment.
However, given this known tool holder it is disadvantageous that the bending segment has a varying flexural strength along its width, the flexural strength being higher in the region of the projection. This results in an inhomogeneous clamping behavior of the clamping segment. Furthermore, the tool holder is quite complicated to manufacture due to the geometry of the rear side of the clamping segment.